FCMP++ and Carrot: What Monero's Biggest Upgrade Changes for You

FCMP++ is the largest change planned for Monero in years. It replaces rings of 16 with a proof that covers the whole chain, and it arrives together with Carrot, a new addressing protocol that keeps your current address working. Here is what is confirmed, what is still being tested, and what you should do (and not do) before and on fork day. Every status line on this page was checked against primary sources on 15 October 2026.

The short answer

Today every Monero spend uses a ring signature: your real coin plus 15 decoys, a ring size of 16, as the Monero technical specifications state. The developers describe FCMP++ as a proposed upgrade "to replace ring signatures with membership proofs that span the whole chain." Carrot, released alongside it, is described as a proposed upgrade to Monero's addressing protocol.

In plain words: the crowd you hide in grows from 16 to everyone, and the way wallets find their payments gets safer, without asking you to change your address.

Where FCMP++ stands today

Developers test the upgrade on a stressnet: a separate test network that forks off Monero's testnet, where the coins have no value. The release notes on the seraphis-migration GitHub repository give the dates below.

The v3 notes call it beta software that "will likely have bugs", and list hardware wallets, multisig and transaction proofs as not yet working. In the Research Lab meeting of 7 October 2026, developers confirmed the fork had happened and discussed fixes still in progress, including one found by an external review.

Audits are running in parallel. The FCMP++ integration audit proposal (posted 6 April 2026) splits the review into three phases and showed 0 of 3 milestones complete when we checked. In the 30 September 2026 meeting, the lead integrator said phase 2 code was merged and phase 3 code was open for review, with a request for audit quotes for those phases still to be drafted.

You will read guesses elsewhere, some of them confident. We do not repeat them. A hard fork date is set by the developers when they judge the code and audits ready, and announced through official channels such as getmonero.org. We will update this page when that happens.

From 16 to the whole chain

A ring of 16 is a good hiding place, but a small one. Your wallet picks 15 decoys from past outputs, and an analyst can try to guess the real one from clues such as how old each output is. A 2025 Monero Research Lab post estimates that a well-built guessing attack gets the real spend right about 1 time in 4.2 instead of 1 in 16, and says full-chain membership proofs "eliminate the weaknesses of the ring signature privacy model." Our ring signature guide puts that number in context.

FCMP++ removes the guessing game. Instead of naming 16 candidates, your transaction proves that the coin you spend is one of all eligible outputs on the chain, without saying which. There are no decoys to choose, so there is no decoy pattern to analyse.

What stays the same: receivers are still hidden by one-time stealth addresses, and amounts are still hidden. For the full picture of how the three layers fit, see how Monero works.

Carrot in plain words

Carrot stands for "Cryptonote Address on Rerandomizable-RingCT-Output Transactions." You will never need that name. What matters is what it does for you, according to the Carrot specification:

• Your address keeps working. Carrot keeps backwards compatibility with existing addresses, including subaddresses and integrated addresses. The specification says no wallet key migration is required.
• Known attacks are closed for every wallet. It mitigates the Janus attack (a trick to link two of your addresses) and the burning bug (a way to make received funds unspendable).
• New wallets get new keys. Wallets created under Carrot get a key hierarchy with a view-all tier (a true view-only wallet that sees incoming payments and spends, so it shows the correct balance, but cannot spend) and a generate-address tier (creates receiving addresses without seeing the chain), useful for shop tills.

Other changes you will notice

Custom unlock times go away. On 10 May 2026 the project announced that the custom transaction unlock time is "set to be deprecated at consensus with FCMP++." The post cites security, privacy and fungibility problems, and merchant software that failed to check unlock times. Transactions already created keep their unlock times; transactions created after 1 June 2026 with an unlock time past the fork would unlock when the fork block arrives. This is separate from the normal short lock on newly received funds, which our guide to unlocked balance explains.

A rescan may be needed. On the test network, one fork required existing wallets to be "re-scanned from restore height." Whether mainnet will need the same is not decided in anything we read, so keep your restore height written down with your seed.

Will my wallet work after the fork?

Only once it ships an FCMP++ version. The table shows what we could verify for each wallet, with the date we checked. "No public work found" means we searched the project's public channels and found nothing, not that nothing is happening.

We are open about our own row because it matters: a wallet that is not updated cannot send after a hard fork. If MonkStash is not ready on fork day, we will say so on the site, and your 25-word seed will restore in any updated Monero wallet.

What to do on fork day

When the developers announce a date, this is the whole checklist.

1. Check your seed and restore height before the date
   Make sure your 25 words and restore height are written down and readable. This is your way back no matter which app you use.
2. Update your wallet from its official source
   Get the update from the wallet's own website or app store listing, after the official getmonero.org announcement. Do not follow links in DMs, ads or search results.
3. Ignore anyone offering to upgrade your coins
   A big upgrade is an easy story for scammers: fake "migration" sites, "claim your new coins" offers and support impersonators. No real upgrade asks for your seed or for you to send coins. Our guide to Monero phishing sites shows the common tricks.
4. Avoid sending during the switch
   The 7 October 2026 meeting notes that some valid transactions might be dropped at a fork and would need to be made again. Unless it is urgent, wait until your wallet shows it is synced on the new rules.
5. If your app is not ready, wait
   Your coins are on the chain, not in the app. They will be there when your app updates, or you can restore your seed in an updated wallet.

Next steps

Nothing to do today, except keep your backup safe and learn what is changing. Start with how ring signatures work to see what FCMP++ replaces, then stealth addresses and subaddresses, the parts Carrot keeps compatible. If you want a private wallet that runs in your browser while we work on FCMP++ support, open MonkStash, and follow our progress on the roadmap.